1. Field of the Invention
The present invention relates to a liquid discharge head that carries out recording by discharging liquid, such as ink, and a method of producing a liquid discharge head.
2. Description of the Related Art
Recently, there has been a need for high-speed recording using inkjet recording apparatuses, and in response, full-line liquid discharge heads, which have a width equal to the width of a recording medium, such as paper, have been considered for use in inkjet recording apparatuses.
As an example of such a full-line liquid discharge head, FIG. 1 in Japanese Patent Laid-Open No. 2007-296638 illustrates a configuration of element substrates, each including energy generating elements and discharge ports for discharging ink.
With a liquid discharge head having such a configuration, element substrates and flexible wiring substrates are disposed on a supporting member and the arranged element substrates and wiring substrates are electrically connected.
Each wiring substrate applies electrical signals instructing ink discharge to a corresponding element substrate, has an opening in which the corresponding element substrate is disposed, and is adhesively secured onto the main surface of the supporting member.
With such a full-line liquid discharge head, the element substrates and the wiring substrates, which have a relatively large area, are electrically connected. When connected, the wiring substrates may expand and/or contract due to heat generated during production and/or while performing recording.
To prevent the electrical connection between the element substrates and the wiring substrates from failing due to expansion and/or contraction of the wiring substrates, it is desirable to provide an electrical connection by wire bonding using wires made of, for example, gold.
The flexible wiring substrates are made of a flexible, thin material.
When such a thin wiring substrate is bonded to the supporting member and wire-bonded to a corresponding element substrate, the following problem occurs.
When an excessive amount of adhesive is applied between the wiring substrate and the supporting member and the wiring substrate and the supporting member are pressed together for bonding, the adhesive flows out from between the wiring substrate and the supporting member to the upper surface of the wiring substrate.
Since the wiring substrate is extremely thin, e.g., 0.15 mm, sometimes the adhesive moves up the end surface of the opening in the wiring substrate along the electrical terminals of the wiring substrate and spreads to the bonding points of the wires.
The adhesive covering the bonding points in such a manner adversely affects the subsequent wire bonding.
When the amount of adhesive is reduced in consideration of such spreading of the adhesive, the adhesive does not reach the edge of the opening in the wiring substrate and forms a space not filled with the adhesive between the wiring substrate and the supporting member.
If such a space is formed near a bonding point, ultrasonic energy is dispersed during wire bonding, having an adverse effect on the wire bonding.
Accordingly, it is necessary to precisely control the amount of adhesive, but such precise control carried out during the production process may reduce productivity.
In inkjet recording, it is desirable that the distance between the discharge port surface of the liquid discharge head and the recording medium (paper distance) be small to increase the impact precision of the discharged ink droplets to achieve high-quality recording.
Electrical connection established by wire bonding, such as that described above, causes the paper distance to be large because the wires are arc shaped.